Hitherto, as a reverse osmosis membrane having a structure different from that of an asymmetric reverse osmosis membrane, a composite reverse osmosis membrane comprising a microporous supporting membrane having formed thereon an active thin membrane having substantially selective separation property is known.
At present, as such a composite reverse osmosis membrane, many composite reverse osmosis membranes wherein a thin membrane comprising a polyamide obtained by an interfacial polymerization of a polyfunctional aromatic amine and a polyfunctional aromatic acid halide is formed on a supporting membrane are known as described in, e.g., JP-A-55-147106, JP-A-62-121603, JP-A-63-218208, and JP-A-2-187135 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
Also, composite reverse osmosis membranes wherein a thin membrane comprising a polyamide obtained by an interfacial polymerization of a polyfunctional aromatic amine and polyfunctional alicyclic acid halide is formed on a supporting membrane are known as described in, e.g., JP-A-62-258705 and JP-A-63-218208.
The above-described composite reverse osmosis membranes have a high desalinating property and a high water permeability, but in a recent ultrapure water production system, it has been required to increase the purity of water by a membrane only by reducing the amount of ion-exchange resins used. For example, it has been required to reduce the electrical conductivity of water to the same extent as the case of using ion-exchange resins by using reverse osmosis membranes in two stages. Also, with the increase of the capacity of semiconductors, cleaner ultrapure water has been required and for satisfying the requirement, the conventional composite reverse osmosis membranes are insufficient and a composite reverse osmosis membrane having a higher desalting property and a higher water permeability has been demanded.
Also, aromatic or alicyclic polyvalent acid chlorides are widely used as polymeric material-producing raw materials such as crosslinking agents, condensing agents, etc. An aromatic polyvalent acid chloride generally forms a rigid condensation product but has problems that the reactivity is poor, etc. On the other hand, an alicyclic polyvalent acid chloride shows a good reactivity but the condensation product is flexible, causing a problem according to the use.
Thus, from the standpoint of forming a rigid condensation product while maintaining the good reactivity of an alicyclic polyvalent acid chloride, a polyvalent acid chloride comprising a bicyclo ring has been given attention.
However, the polyvalent acid chloride comprising a bicyclo ring has problems in the stability of the acid chloride, the danger in the case of producing (synthesizing) the acid chloride, the troublesomeness of the production (synthesis) steps, the low yield, and the difficulty of obtaining the raw material as an alicyclic polyvalent acid chloride. Thus, the production of such a polyvalent acid anhydride has scarcely practiced.
Furthermore, different from the aromatic polyvalent acid chloride, the polyvalent acid chloride include various kinds of isomers and from the dispersion of the reactivities among the isomers, there is a problem that a stable condensation product is not obtained in the case that the ratio of the isomers is different.
However, recently, the investigations on a polyvalent acid chloride comprising a bicyclo ring which is considered to have both the advantages of an aromatic polyvalent acid chloride and an alicyclic polyvalent acid chloride have been proceeded, and the interest of such a polyvalent acid chloride as polymeric material-producing raw materials such as crosslinking agents, condensing agents, esterifying agents, amidating agents, acylating agents, etc., has been increased.
Thus, in the industry, the development of an excellent novel acid chloride which can be safely and widely utilized as polymeric material-producing raw materials has been desired.